The approval moves the long-discussed project closer to construction, though board members attached a condition: developers must resolve parking before anything else proceeds. County Planning Director James Hunt said after the vote that work cannot begin until the parking situation is settled, with a goal of resolving it by spring.

The venue would encompass more than 447,000 square feet, with an exterior height of just over 300 feet and an interior height of 214 feet. Four LED video panels would serve as the main signage, a scale planning staff said is comparable to signage already approved for MGM. Renderings presented Thursday show the Sphere from the south side of National Harbor, with the Capital Wheel in the background, and from Oxon Hill Manor, where it would appear just above the trees.

Developers sought to reassure the board and nearby residents that the structure's glow will not spill beyond the property. A staff report presented by Jill Kosack concluded that while the exterior — referred to as the exosphere — will be a visible architectural feature, ground illumination will be limited beyond the immediate area, falling off entirely beyond 69 feet from the base. The report noted that brightness is heavily influenced by the colors displayed, as well as atmospheric conditions, viewing angle and distance.

"There would not be any type of light pollution coming outside of the property itself," Hunt said. He added that the information presented indicated the lighting would be less intrusive than what emanates from the Sphere in Las Vegas. "They know this is a different area, different community, so they really, really wanted to cater to this community," he said.

Dan Gray, who helped lead the design, said the project was consciously sited as part of the larger Beltway parcel and National Harbor development. "Unique, but in harmony with the vision for the larger development of the area," Gray said. He promised the exterior would fit the character of the surrounding area.

Tony Basalari, vice president of business development at Sphere, noted that National Harbor already draws more than 15 million visitors a year. "This project builds on that vision," he said.

The plans include a 2,100-space parking garage to be built nearby once a site is chosen, along with access for rideshare and shuttle buses. Staff recommended that the garage be fully constructed before the Sphere opens to the public. The site plan also allocates space for bicyclists to ride and park.

An elevated, enclosed pedestrian walkway would connect the Sphere to a parcel across the ramp to Interstate 295, where rideshare drivers could drop off and pick up visitors. Sphere leaders said enclosing the bridge would make it usable in any weather.

"Sphere is all about being transported through immersive entertainment," Gray said. "The journey and excitement begin long before and remain long after the show has ended."

John Peterson, whose father helped create National Harbor, told the board there had been "many offers before to do something. And we said, 'We're waiting for the right use.' There's no better use that we could ever have voted for." Peterson said visitors could exit within 30 minutes of a show's end.

A handful of residents testified against the project, raising skepticism about economic promises, visual impacts and traffic. Many of those concerns fall outside the planning board's purview and could not be considered in the site plan review. The board's discussion stayed focused on physical characteristics within and around the structure.

Commissioner Gloria Lawlah, after recounting the history of National Harbor's development on the Potomac, including efforts to attract the Gaylord hotel, said the approval brought tears to her eyes. "It's a wonderful opportunity" for the county, she said, describing public opposition as healthy and beneficial for the project. Commissioner Billy Okoye told the public their concerns were being taken seriously, adding that the venue will be something people enjoy "for generations to come."

The project still requires the parking issue to be resolved before construction can begin, with county officials aiming for a spring resolution.